hi, my system is powerpc. i am attempting to map logical address
returned by kmalloc to the user program. the code below doesn't
accomplish that task. please let me know what i am doing wrong...thank
you in advance.

here's the driver:


#include
#include
#include
#include

#include /* printk() */
#include /* kmalloc() */
#include /* everything... */
#include /* error codes */
#include /* size_t */
#include
#include
#include
#include

#include
#include
static unsigned char *buffer;
static int simple_major = 0;
module_param(simple_major, int, 0);
MODULE_AUTHOR("Jonathan Corbet");
MODULE_LICENSE("Dual BSD/GPL");

/*
* Open the device; in fact, there's nothing to do here.
*/
static int simple_open (struct inode *inode, struct file *filp)
{
return 0;
}


/*
* Closing is just as simpler.
*/
static int simple_release(struct inode *inode, struct file *filp)
{
return 0;
}



/*
* Common VMA ops.
*/

void simple_vma_open(struct vm_area_struct *vma)
{
printk(KERN_NOTICE "Simple VMA open, virt %lx, phys %lx\n",
vma->vm_start, vma->vm_pgoff << PAGE_SHIFT);
}

void simple_vma_close(struct vm_area_struct *vma)
{
printk(KERN_NOTICE "Simple VMA close.\n");
}


/*
* The remap_pfn_range version of mmap. This one is heavily borrowed
* from drivers/char/mem.c.
*/

static struct vm_operations_struct simple_remap_vm_ops = {
.open = simple_vma_open,
.close = simple_vma_close,
};

static int simple_remap_mmap(struct file *filp, struct vm_area_struct
*vma)
{

if (remap_pfn_range(vma, vma->vm_start,
virt_to_phys((unsigned long)(buffer)) >>
PAGE_SHIFT,
vma->vm_end - vma->vm_start,
vma->vm_page_prot))
return -EAGAIN;

/*
if (io_remap_page_range(vma, vma->vm_start,
virt_to_phys((unsigned int)buffer),
vma->vm_end - vma->vm_start,
vma->vm_page_prot))
return -EAGAIN;
*/

/*
if (remap_pfn_range(vma, vma->vm_start,
((int)(buffer)) >> PAGE_SHIFT,

vma->vm_end - vma->vm_start,
vma->vm_page_prot))
return -EAGAIN;
*/
vma->vm_ops = &simple_remap_vm_ops;
simple_vma_open(vma);
return 0;
}


/*
* Our various sub-devices.
*/
/* Device 0 uses remap_pfn_range */
static struct file_operations simple_remap_ops = {
.owner = THIS_MODULE,
.open = simple_open,
.release = simple_release,
.mmap = simple_remap_mmap,
};


/*
* We export two simple devices. There's no need for us to maintain
any
* special housekeeping info, so we just deal with raw cdevs.
*/
static struct cdev SimpleDevs;

/*
* Module housekeeping.
*/
static int simple_init(void)
{
int result;
dev_t dev = MKDEV(simple_major, 0);
int err, devno;

/* Figure out our device number. */
result = alloc_chrdev_region(&dev, 0, 2, "simple");
simple_major = MAJOR(dev);

if (result < 0) {
printk(KERN_WARNING "unable to get major %d\n",
simple_major);
return result;
}
simple_major = result;

printk(KERN_WARNING "simple: major %d\n", simple_major);

devno = MKDEV(simple_major, 0);

cdev_init(&SimpleDevs, &simple_remap_ops);
SimpleDevs.owner = THIS_MODULE;
SimpleDevs.ops = &simple_remap_ops;
err = cdev_add (&SimpleDevs, devno, 1);
/* Fail gracefully if need be */
if (err)
printk (KERN_NOTICE "Error %d adding", err);


buffer = kmalloc(4096, GFP_KERNEL);
if (!buffer) {
printk(KERN_ALERT "kmalloc failed \n");
return -1;
}
*buffer = '\0';

return 0;
}


static void simple_cleanup(void)
{
cdev_del(&SimpleDevs);
unregister_chrdev_region(MKDEV(simple_major, 0), 1);
if (buffer)
kfree(buffer);
}


module_init(simple_init);
module_exit(simple_cleanup);
--------------------------------------------------------------------


my make file:

# Comment/uncomment the following line to disable/enable debugging
#DEBUG = y
# Add your debugging flag (or not) to CFLAGS
ifeq ($(DEBUG),y)
DEBFLAGS = -O -g # "-O" is needed to expand inlines
else
DEBFLAGS = -O2
endif

CFLAGS += $(DEBFLAGS) -I$(LDDINCDIR)

ifneq ($(KERNELRELEASE),)
# call from kernel build system

obj-m := simple.o

else

KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)

default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) LDDINCDIR=$(PWD)/../include modules

endif

clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions

depend .depend dep:
$(CC) $(CFLAGS) -M *.c > .depend


ifeq (.depend,$(wildcard .depend))
include .depend
endif

----------------------------------------------------------------------------------------

my test program:


#include
#include
#include
#include
#include
#include
#include

int main (int argc, char *argv[])
{
char *str;
int fd;


fd = open("/dev/simple", O_RDWR);

str = (char *)mmap(NULL,getpagesize(),
PROT_READ | PROT_WRITE,
MAP_SHARED,fd,0);

if (str==MAP_FAILED) {
perror("mmaptest user ");
return 1;
};

/* there you go */
printf("\n!!!!!!!!!!!!%s\n\n", str);

munmap(str, 4096);
close(fd);

return 0;
}